Sga_target

Type:Big integer
Syntax:SGA_TARGET = integer [K | M | G]
Default:0 (SGA autotuning is disabled)
Modify:Yes
Range:ALTER SYSTEM
Basic:64 MB to operating system-dependent
Rac:Yes
Notes:SGA_TARGET specifies the total size of all SGA components. If SGA_TARGET is specified, then the following memory pools are automatically sized:

■ Buffer cache (DB_CACHE_SIZE)

■ Shared pool (SHARED_POOL_SIZE)

■ Large pool (LARGE_POOL_SIZE)

■ Java pool (JAVA_POOL_SIZE)

■ Streams pool (STREAMS_POOL_SIZE)

If these automatically tuned memory pools are set to nonzero values, then those values are used as minimum levels by Automatic Shared Memory Management. You would set minimum values if an application component needs a minimum amount of memory to function properly.
The following pools are manually sized components and are not affected by Automatic Shared Memory Management:

■ Log buffer

■ Other buffer caches, such as KEEP, RECYCLE, and other block sizes

■ Fixed SGA and other internal allocations

The memory allocated to these pools is deducted from the total available for SGA_TARGET when Automatic Shared Memory Management computes the values of the automatically tuned memory pools.